1. Field of the Invention
The present invention relates to a silencer. More particularly, the invention relates to a silencer effective in reducing and canceling pulsation and noise produced in the intake air and in the exhaust gas of gas compressors, such as in the intake air, exhaust gas, air and coolant of internal combustion reciprocating engines as represented by gasoline engines and diesel engines.
2. Description of the Prior Art
A variety of silencers (mufflers) have heretofore been proposed. In order to cope with noise and vibration, and to reduce and cancel pulsation in the intake air and in the exhaust gas, there have been proposed those which are in principle of the attenuation type, resonance type, sound-absorbing type, or a combination thereof.
In particular, in order to cope with noise and vibration of reciprocating engines and gas compressors, the silencers of the resonance type and attenuation type have chiefly been employed, and the study has been forwarded to a considerable degree concerning the structure and theory thereof.
For instance, Japanese Unexamined Patent Publication (Kokai) No. 155521/1984 teaches a silencer chiefly for the diesel engines having an additional by-pass exhaust pipe to deviate the phase of pulsation in the exhaust gas, so that the loop of a waveform A in a main exhaust pipe and a loop of a waveform B in the by-pass exhaust pipe are brought into agreement in a plus-to-minus relationship to reduce or cancel the amplitude of pulsation. However, this prior art involves a problem in that it is difficult to evenly distribute the exhaust gas stream into the main exhaust pipe and the by-pass exhaust pipe, which has not been solved yet.
In general, it is more difficult to reduce and cancel the pulsation in the intake air and in the exhaust gas in a region of low frequencies than in a region of high frequencies. At present, there has not still been provided the last silencer which is light in weight, compact in size and is effective in reducing undulation in the medium- to low-frequency regions.